Topic: connecting the RME ADI-2 to Mac-Mini

I have the RME ADI-2 with an optical in/out to the Mac-mini....and selected "Digital" In/Out as the source. I was recently told "your Mac is the master clock. The RME is only doing the A/D conversion and using a really poor consumer grade clock source as the master, which is pretty much defeating the purpose of using better converters."
Is this right? If so, how can I fully utilize the conversion of the ADI-2?


Re: connecting the RME ADI-2 to Mac-Mini

Whoever told you this doesn't know about the SteadyClock built inside the ADI-2.

Matthias Carstens

3 (edited by tokyofan 2011-08-01 14:50:48)

Re: connecting the RME ADI-2 to Mac-Mini

So, I'm OK? I have a toslink connection to my Mac-mini.

This same guy explained further:

[q]If your sample rate is say 44.1kHz, this means that 44,100 times a second your analogue to digital converter (ADC) is measuring and digitising the incoming waveform. Each of these measuring points is called a Sample Point. In an ideal world, these 44,100 sample points would be spaced perfectly evenly per second. Unfortunately in the world, a perfect clocking design does not exist. The difference between a theoretically perfect clock design and the real world performance of a clock in an ADC is called Jitter and is often measured in Pico Seconds (ps). There has been a fair amount of research and debate about the perceptual effects of jitter and there is some evidence to suggest that even jitter in the nano-second (billionths of a second) range can be perceived as a loss of sound quality. Converter (and other digital audio equipment) manufacturers therefore go to considerable lengths to design elaborate clocking systems to reduce jitter. To give you an example, the most extreme clocking system for audio I know of is made by Antelope and employs an internally refrigerated rubidium (atomic) clock!

In other words, a fair percentage of the money you spent on your converter paid for a professional grade internal clock. You have now effectively bypassed that professional grade clock and replaced it with the consumer grade clock in your Mac, which probably cost about $5!

One last point (as a by the way), there are a number of different points within the clocking systems employed by manufacturers where jitter can be measured. Unfortunately, there is no agreed standard of where exactly in the system jitter should be measured. This means, as a general rule, that you cannot compare one manufacturer's jitter specifications with another which makes the publication and advertising of jitter specifications pretty much useless![/q]

Re: connecting the RME ADI-2 to Mac-Mini

Tell him to read this: … teadyclock

Daniel Fuchs

5 (edited by tokyofan 2011-08-02 14:52:09)

Re: connecting the RME ADI-2 to Mac-Mini

I asked the vendor where I bought the RME ADI-2 and he wrote:

[q]Yes, your Mac is the clock master in this case, but the A/D conversion on the ADI2 is better than the A/D conversion in the Mac, so there should still be an improvement. Yes, the ADI2 could sounds better if it were the clock master. There is not a way to do this without adding a USB, Firewire, or PCI slot card that has digital connections that are bi-directional. Your MBox would service this purpose.

[q]Yes to running it through the MBox3, as both the MBox3 clock, and the clock in the ADI2 are superior to the clock in the Mac. As the ADI2 does not have a word clock connection, you need to have a digital cable on the RCA or Optical connection coming from the ADI2 to the MBox3 in order for the MBox3 and thus the Mac be a slave to the ADI2 clock. USB or firewire does not matter in this instance.

Initially I would think that if you have the ADI selected as the master clock in the Mac Audio/MIDI settings, it should be providing the clock, if you can select it as the master clock.
So, would the ADI2 work better for recording by connecting it to the Mbox and choosing the Mbox as my default sound device? Or would any improvements be marginal?

Also, with a TOSLINK connection to the Mac-mini, are these the right settings?
- INPUT LEVEL to Lo Gain
- OUTPUT LEVEL to Hi gain
- set the CLOCK to INP (i.e. the only dot that doesn't have a number of letters beside it)
- INPUT set to OPT